1. Field
The presently disclosed subject matter relates to semiconductor light-emitting devices in which light emitted from a semiconductor light-emitting chip is wavelength-converted by a wavelength converting layer, and to manufacturing methods for the same. More particularly, the disclosed subject matter relates to semiconductor light-emitting devices for a vehicle light and the like, which can emit various color lights having a substantially uniform color tone and a high light-emitting efficiency from a small light-emitting surface, and to methods of manufacturing such devices.
2. Description of the Related Art
Semiconductor light-emitting devices, in which a part of the light emitted from a semiconductor light-emitting chip is converted into light having a different wavelength by a phosphor and in which a mixture light including the light having the different wavelength mixed with the light emitted directly from the semiconductor light-emitting chip is emitted, have been known as semiconductor light source(s) for various lighting units. In this case, the semiconductor light-emitting devices are usually provided with a wavelength converting layer including a phosphor particle on or over the semiconductor light-emitting chip such as an LED chip, etc.
A conventional semiconductor light-emitting device including such a wavelength converting layer, for example, is disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open JP2010-219324). FIGS. 9a and 9b are respectively a top view and a side cross-sectional view taken along line A-A in FIG. 9a showing the conventional semiconductor light-emitting device, which may be used as a light source for general lighting and the like and which is disclosed in Patent Document No. 1.
The conventional semiconductor light-emitting device 300 includes: a mounting board 50; a conductor pattern 51 formed on the mounting board 50; a frame 55 formed in a tubular shape and being located on the mounting board 50; a semiconductor light-emitting chip 60 mounted on the conductor pattern 51: an optical transparent material 70 including a wavelength converting layer and being located on the semiconductor light-emitting chip 60 via a light-transmitting material 80; a sealing material 40 including a light-reflecting material 45 and being disposed between the frame 55 and at least the optical transparent material 70; and a light-emitting surface 90 exposed from a top surface of the optical transparent material 70 as a light-emitting surface of the device 300 so as to be able to emit a wavelength converted light.
In this case, when the semiconductor light-emitting chip 60 is a blue LED chip emitting blue light and the optical transparent material 70 is composed of the wavelength converting layer including a yellow phosphor, which can emit a yellow light upon being excited by the blue light emitted from the blue LED chip, the semiconductor light-emitting device 300 can emit substantially white light from the light-emitting surface 90, by an additive color mixture of the excited yellow light emitted from the yellow phosphor and a part of the blue light emitted from the blue LED chip.
In the conventional semiconductor light-emitting device having such a structure, the sealing material 40 including the light-reflecting material 45 is frequently disposed between the frame 55 and the optical transparent material 70 including the wavelength converting layer, the semiconductor light-emitting chip 60, etc. to improve a light-emitting efficiency of the device. However, in the conventional light-emitting device, such structure may be subject to color variability in the wavelength converted light.
For example, when the semiconductor light-emitting device 300 is configured to emit substantially white light, in which an additive color mixture of the excited yellow light emitted from the yellow phosphor and the part of the blue light emitted from the blue LED chip is employed, bluish white light may be emitted from a central portion of the light-emitting surface 90 and yellowish white light may be emitted from an outer portion of the light-emitting surface 90.
Meanwhile, it has been understood that a color temperature of the wavelength converted light varies according to a density of the phosphor contained in the wavelength converting layer. That is because the amount of the excited light varies in accordance with the amount of phosphor contained in the wavelength converting layer. Accordingly, it is understood that the density of the phosphor can be higher to increase the original light except the excited light in light emitted from the semiconductor light-emitting chip and also a thickness of the wavelength converting layer becomes thicker.
However, when the density of the phosphor becomes higher and/or the thickness of the wavelength converting layer becomes thicker, a light-emitting loss may be large, and therefore a light-emitting efficiency of the semiconductor light-emitting device may increase. Additionally, when the semiconductor light-emitting devices are used as a light source for a lighting unit such as a vehicle headlight, which controls light emitted from the light-emitting devices using a reflector and/or a projector lens, a light-emitting device having a small light-emitting surface may be desired to efficiently control light emitted from the light-emitting device with a small optical structure.
Hence, another conventional semiconductor light-emitting device having a small light-emitting surface can be used as a light source for a vehicle headlight using a projector lens and is disclosed in Patent Document No. 2 (U.S. patent application Ser. No. 13/162,151, U.S. Patent Publication No. US 2011/0309388 A1). Patent Document No. 2 discloses a small light-emitting surface, which is slightly larger than a top surface of a semiconductor light-emitting chip.
The above-referenced Patent Documents are listed below, and are hereby incorporated with their English abstracts in their entireties.    1. Patent Document No. 1: Japanese Patent Application Laid Open JP2010-219324.    2. Patent Document No. 2: U.S. patent application Ser. No. 13/162,151, U.S. Patent Publication No. 2011-0309388 A1.    3. Patent Document No. 3: U.S. Patent Publication No. 2012-0025218-A1.    4. Patent Document No. 4: U.S. Divisional patent application (Parent U.S. patent application Ser. No. 12/720,819, U.S. Pat. No. 8,251,560.    5. Patent Document No. 5: U.S. Patent Application No. 2012-0320617 A1
The disclosed subject matter has been devised to consider the above and other problems, features, and characteristics. Thus, embodiments of the disclosed subject matter can include semiconductor light-emitting devices that can emit a wavelength converted light having a substantially uniform color tone and a high light-emitting efficiency from a small light-emitting surface, which is smaller than a top surface of a semiconductor light-emitting chip, and associated manufacturing methods that do not cause and/or are designed to prevent some of the above-described problems, concerns, and characteristics related to a wavelength converting layer and/or lighting device. The disclosed subject matter can also include a semiconductor light-emitting device using a plurality of semiconductor light-emitting chips that can be used for wavelength-converting light having a substantially uniform color tone and a high light-emitting efficiency.